﻿Shader "Study/Chapter7/RampTexture"
{
	//渐变纹理
	Properties
	{
		_Color("Color Tint",Color) = (1,1,1,1)		
		_MainTex("Main Text",2D) = "white" {}
		_Specular("Specular",Color) = (1,1,1,1)
		_Gloss("Gloss",Range(8.0,256)) = 20
	}
	SubShader
	{
		Pass
		{
			Tags { "LightMode"="ForwardBase" }
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			
			#include "Lighting.cginc"
			
			fixed4 _Color;
			sampler2D _MainTex;
			float4 _MainTex_ST;
			fixed4 _Specular;
			float _Gloss;
			
			struct a2v
			{
				float4 vertex:POSITION;
				float3 normal:NORMAL;
				float4 texcoord:TEXCOORD;
			};

			struct v2f
			{
				float4 pos:SV_POSITION;
				fixed3 worldNormal:TEXCOORD;
				fixed3 worldPos:TEXCOORD1;
				fixed2 uv:TEXCOORD2;
			};
			
			//顶点
			v2f vert(a2v v)
			{
				v2f o;	
				o.pos = mul(UNITY_MATRIX_MVP,v.vertex);

				o.worldNormal = UnityObjectToWorldNormal(v.normal);
				o.worldPos = mul(_Object2World,v.vertex).xyz;
				o.uv = v.texcoord.xy * _MainTex_ST.xy+ _MainTex_ST.zw;
				
				return o;
			}
			
			float4 frag (v2f i) : SV_Target
			{
				fixed3 worldNormal = normalize(i.worldNormal);
				fixed3 worldLightDir = normalize(UnityWorldSpaceLightDir(i.worldPos));
				
				fixed3 albedo= tex2D(_MainTex,i.uv).rgb * _Color.rgb;
				fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz *albedo;
				fixed3 diffuse = _LightColor0.rgb *albedo *max(0,dot(worldNormal,worldLightDir)); 
				fixed3 viewDir = normalize(UnityWorldSpaceViewDir(i.worldPos));
				fixed3 halfDir = normalize(worldLightDir +viewDir);
				fixed3 specular = _LightColor0.rgb * albedo * pow(max(0,dot(worldNormal,worldLightDir)),_Gloss);

				//返回顶点颜色
				fixed3 vertexColor = ambient + diffuse + specular;
				return fixed4(vertexColor,1.0);
			}
			ENDCG
		}
	}

	FallBack "Specular"
}
